Optical information recording method, optical information recording device and optical information recording medium

ABSTRACT

An optical information recording device includes a linear velocity setting circuit for setting a first linear velocity v 1  and a second linear velocity v 2  higher than the first linear velocity v 1  for a optical information recording medium, a recording pulse generation circuit for generating a recording pulse signal, depending on the setting by the linear velocity setting circuit, and a laser drive circuit for irradiating the medium with the laser light based on the recording pulse signal generated by the recording pulse generation circuit. The laser drive circuit controls a power level of the laser light so that Pbt 1≦ Pe 1  and Pe 2&lt; Pbt 2≦ Pwa 2 , where Pbt 1  represents a first inter-pulse power level indicating a power level between recording pulses for the first linear velocity v 1 , Pbt 2  represents a second inter-pulse power level indicating a power level between the recording pulses for the second linear velocity v 2 , Pwa 2  represents a recording power level indicating a power level of the recording power for the second linear velocity v 2 , Pe 1  represents a first erase power level indicating a power level of the erase power for the first linear velocity v 1 , and Pe 2  represents a second erase power level indicating a power level of the erase power for the second linear velocity v 2.

TECHNICAL FIELD

The present invention relates to a recording/reproduction method and arecording/reproduction device for recording/reproducing data onto/froman optical information recording medium. More particularly, the presentinvention relates to a method for generating a recording pulse waveformfor a medium on which recording is performed using a plurality ofdifferent linear velocities.

BACKGROUND ART

Recently, optical discs, optical cards, optical tapes and the like havebeen proposed and developed as media for recording data optically. Amongthem, the optical disc has attracted attention as a medium capable ofrecording/reproducing data with large capacity and high density.

For example, in the case of a phase change optical disc,recording/reproduction of data is performed using a method that isdescribed in the following. A recording layer of an optical disc isirradiated with laser light (this power level is referred to as arecording power level and is represented by Pw) that is focused using anoptical head and is stronger than a reproduction power, to cause thetemperature of the recording layer to rise and exceed the melting point.After the laser light goes through, a melted portion is cooled rapidlyto form a mark in an amorphous state. Alternatively, the recording layeris irradiated with focused laser light that causes the temperaturethereof to rise up to the crystallization temperature or more and themelting point or less (this power level is referred to as an erase powerlevel, which is represented by Pe) so that an irradiated portion of therecording layer is changed into a crystallized state.

In this manner, a recording pattern including a mark that is anamorphous region and a space that is a crystalline region is formed on amedium, corresponding to a data signal. Data is reproduced by utilizinga difference in reflectance between the crystalline and amorphousregions.

As described above, in order to form a mark on a medium, laser lightneeds to be modulated and emitted so that the power level thereof isbetween the erase power level and the recording power level. A pulsewaveform used for this modulation is referred to as a recording pulse. Anumber of recording methods for forming one mark using a plurality ofrecording pulses is known. The plurality of recording pulses arereferred to as a recording pulse sequence.

At present, CLV (constant linear velocity) recording mainly is used foroptical information recording media, such as recording DVD and the like.This is a recording technique in which a linear velocity, a transferrate and a linear density are substantially constant over the entiresurface of a medium. In this case, the rotational speed of a mediumvaries depending on the recording/reproduction position (i.e., radialposition) on the medium.

In contrast to this, a CAV (constant angular velocity) recordingtechnique has been proposed in which the rotational speed and lineardensity of a medium are substantially constant on the entire surface ofthe medium. In the CAV recording technique, it is not necessary tocontrol the rotational speed of a spindle motor that rotates a medium.Therefore, the spindle motor and its control circuit advantageously canbe produced with low cost. In addition, it is not necessary to suspendrecording/reproduction until a predetermined rotational speed isattained after seeking of a recording/reproduction position, whereby thespeed of access to a medium can be improved.

On the other hand, in this technique, the linear velocity and thetransfer rate vary depending on the recording/reproduction position on amedium. Therefore, conditions for laser light irradiation andheating/cooling vary depending on the recording/reproduction position ona medium.

Various recording techniques are known for improving signal quality whena plurality of different linear velocities are used to record a medium.One of them is a method of forming a mark in which a recording pulsesequence is used in a manner that the ratio of a recording power withrespect to an erase power is changed or the width of each recordingpulse is changed, depending on the recording linear velocity, asdisclosed in, e.g., Patent Publication 1 (JP 2001-118245A (pages 5–7,FIG. 1)). Also, a method of forming a mark using a recording pulsesequence in which the duty ratio of each recording pulse is increased,depending on an increase in the recording linear velocity (i.e.,increasing the ratio of a pulse width to a channel clock cycle) isdisclosed in, e.g., Patent Publication 2 (JP 2001-222819A (pages 3–5,FIG. 2)). Further, a method of forming one recording mark using arecording pulse composed of one rectangular wave in which recordingpower or a recording pulse width is changed, depending on a recordinglinear velocity, is disclosed in, e.g., Patent Publication 3 (JP 2001-155339A (pages 5–7, FIG. 2)).

However, the above-described conventional recording/reproduction methodhas a problem in that data cannot be recorded with high signal qualityand stability when the range of changing the linear velocity is large.Hereinafter, the problem will be described.

When a recording pulse sequence is used for recording at a high linearvelocity and a high transfer rate, a short channel clock cycle isrequired that is used as a reference for generation of the recordingpulse sequence. However, there are certain rising and falling times forlaser modulation and emission requirements.

FIG. 16 is a diagram showing waveforms of signals for modulating laserlight to record a mark, and a waveform of laser light in a conventionalrecording/reproduction method. For example, as shown in FIG. 16, when ½of a cycle Tw91 of a channel clock signal is longer than the sum of arising time TU1 and a falling time TD1 of laser light, the laser lightcan be modulated and emitted between each of a recording power level Pw,an erase power level Pe and an inter-pulse power level Pbt.

FIG. 17 is a diagram showing other waveforms of signals for modulatinglaser light to record a mark, and another waveform of laser light in aconventional recording/reproduction method. As shown in FIG. 17, when ½of a cycle Tw92 of a channel clock signal is shorter than the sum of arising time TU2 and a falling time TD2 of laser light, the laser lightcannot be modulated between a recording power level Pw and aninter-pulse power level Pbt, so the power level of the laser lightvaries depending on the pulse width of the emitted light. In otherwords, since the power level is unstable during modulation, a markhaving a desired shape cannot be formed stably.

FIG. 18 is a diagram showing still other waveforms of signals formodulating laser light to record a mark, and still another waveform oflaser light in a conventional recording/reproduction method. The methodof increasing the duty ratio of each recording pulse, depending on anincrease in the linear velocity, has the following problem when thelinear velocity is high. Specifically, even when ½ of a cycle Tw93 of achannel clock signal is longer than the sum of the rising time and thefalling time of the laser light, if a width between each pulse isshorter than the sum of the rising time and the falling time of laser,the laser light no longer can be modulated between a recording powerlevel Pw and an inter-pulse power level Pbt as shown in FIG. 18.

FIG. 19 is a diagram showing still other waveforms of signals formodulating laser light to record a mark, and still another waveform oflaser light in a conventional recording/reproduction method. When asingle rectangular wave is used for recording at a low linear velocityand a low transfer rate, the relative velocity between a laser spot anda medium is slow and the width of a recording pulse is long. As aresult, a heat accumulation effect is large with respect to a medium,and therefore, mark distortion is likely to occur.

For example, when a mark is formed onto a phase change optical disc,heat accumulated in a front portion of a mark diffuses into a rearportion of the mark while the rear portion of the mark is beingrecorded. As a result, a larger amount of heat is supplied to the rearportion of the mark than the front portion of the mark on the recordinglayer. Therefore, as shown in FIG. 19, there occurs a phenomenon inwhich a mark 702 formed on a track 701 of a phase change optical dischas a rear portion larger than a front portion of the mark 702 so thatthe shape of the mark 702 is distorted, resulting in a deterioratedquality of a reproduced signal.

Further, the duty ratio of a recording pulse signal is changed along thedirection of a time axis with respect to the waveform of emitted lightby, typically, delaying a recording pulse signal using a delay line orthe like. Therefore, a change along the time axis is discrete.Therefore, in the CAV recording technique, the duty ratio can be changedonly discretely, while the linear velocity changes continuously. As aresult, recording characteristics vary depending on a recording positionin the CAV recording technique.

An object of the present invention is to provide an optical informationrecording method, an optical information recording device and an opticalinformation recording medium that can record/reproduce data onto/fromthe same medium over a wide linear velocity range with stability andhigh signal quality.

[Patent Document 1]

JP 2001-118245A (pages 5–7, FIG. 1)

[Patent Document 2]

JP 2001-222819A (pages 3–5, FIG. 2)

[Patent Document 3]

JP 2001-155339A (pages 5–7, FIG. 2)

DISCLOSURE OF INVENTION

In an optical information recording device according to the presentinvention, a mark or a space having a length corresponding to a lengthof a data recording code is formed by irradiating a rotating opticalinformation recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiation of the laser light with a power being switchedamong a plurality of power levels including at least a recording powerlevel and an erase power level. The device includes a linear velocitysetting circuit for setting a first linear velocity v1 and a secondlinear velocity v2 that is higher than the first linear velocity v1 forthe rotating optical information recording medium; a recording pulsegeneration circuit for generating a recording pulse signal, depending ona result of setting by the linear velocity setting circuit; and a laserdrive circuit for irradiating the optical information recording mediumwith the laser light based on the recording pulse signal generated bythe recording pulse generation circuit. The laser drive circuit controlsa power level of the laser light in such a manner that Pbt1≦Pe1 andPe2<Pbt2≦Pwa2 is satisfied, where Pbt1 represents a first inter-pulsepower level indicating a power level between recording pulses for thefirst linear velocity v1, Pbt2 represents a second inter-pulse powerlevel indicating a power level between the recording pulses for thesecond linear velocity v2, Pwa2 represents a recording power levelindicating a power level of the recording power for the second linearvelocity v2, Pe1 represents a first erase power level indicating a powerlevel of the erase power for the first linear velocity v1, and Pe2represents a second erase power level indicating a power level of theerase power for the second linear velocity v2.

In another optical information recording device according to presentinvention, a mark or a space having a length corresponding to a lengthof a data recording code is formed by irradiating a rotating opticalinformation recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiation of the laser light with a power being switchedamong a plurality of power levels including at least a recording powerlevel and an erase power level. The device includes a linear velocitysetting circuit for setting a first linear velocity v1 and a secondlinear velocity v2 that is higher than the first linear velocity v1 forthe rotating optical information recording medium; a recording pulsegeneration circuit for generating a recording pulse signal, depending ona result of setting by the linear velocity setting circuit; and a laserdrive circuit for irradiating the optical information recording mediumwith the laser light based on the recording pulse signal generated bythe recording pulse generation circuit. The laser drive circuit controlsa power level of the laser light in such a manner that Pbt1≦Pe1 andPe2<Pwb2<Pwa2 is satisfied, and a waveform of the laser light for thesecond linear velocity v2 is set to be a stepwise waveform such that arecording pulse of the power level Pwb2 is provided immediately after arecording pulse of the power level Pwa2, where Pbt1 represents a firstinter-pulse power level indicating a power level between recordingpulses for the first linear velocity v1, Pwa2 represents a recordingpower indicating a power level of the recording power for the secondlinear velocity v2, Pwb2 represents a second recording power indicatinga power level of a second recording power for the second linear velocityv2, Pe1 represents a first erase power level indicating a power level ofthe erase power for the first linear velocity v1, and Pe2 represents asecond erase power level indicating a power level of the erase power forthe second linear velocity v2.

In still another optical information recording device according to thepresent invention, a mark or a space having a length corresponding to alength of a data recording code is formed by irradiating a rotatingoptical information recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiation of the laser light with a power being switchedamong a plurality of power levels including at least a recording powerlevel and an erase power level. The device includes a linear velocitysetting circuit for setting a first linear velocity v1, which is a lowerlimit, and a second linear velocity v2, which is an upper limit, withrespect to the rotating optical information recording medium, arecording pulse generation circuit for generating a recording pulsesignal, depending on a result of setting by the linear velocity settingcircuit, and a laser drive circuit for irradiating the opticalinformation recording medium with the laser light based on the recordingpulse signal generated by the recording pulse generation circuit.Pbt1≦Pe1 and Pe2<Pwb2<Pwa2 are satisfied, the laser light is irradiatedwhile switching powers among the recording power level, the first erasepower level and the first inter-pulse power level, when the linearvelocity v is v1<v<v0, a waveform of the laser light is set to be astepwise waveform such that a recording pulse of the power level Pwb2 isprovided immediately after a recording pulse of the power level Pwa2,when the linear velocity v is v0<v<v2, and the power level Pwb of thesecond recording power is controlled so that (Pwb−Pe) is increased,depending on an increase in the linear velocity v. Pbt1 represents afirst inter-pulse power level indicating a power level between recordingpulses for the first linear velocity v1, Pwa2 represents a recordingpower indicating a power level of the recording power for the secondlinear velocity v2, Pwb2 represents a second recording power indicatinga power level of a second recording power for the second linear velocityv2, Pe1 represents a first erase power level indicating a power level ofthe erase power for the first linear velocity v1, Pe2 represents asecond erase power level indicating a power level of the erase power forthe second linear velocity v2, v1<v0<v2 is satisfied, Pwb represents apower level of the second recording power for a linear velocity v ofv1<v<v2, and Pe represents a power level of the erase power for thelinear velocity v.

In still another optical information recording device according to thepresent invention, a mark or a space having a length corresponding to alength of a data recording code is formed by irradiating a rotatingoptical information recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiation of the laser light with a power being switchedamong a plurality of power levels including at least a recording powerlevel and an erase power level. The device includes a linear velocitysetting circuit for setting a first linear velocity v1, which is a lowerlimit, and a second linear velocity v2, which is an upper limit, withrespect to the rotating optical information recording medium, arecording pulse generation circuit for generating a recording pulsesignal, depending on a result of setting by the linear velocity settingcircuit, and a laser drive circuit for irradiating the opticalinformation recording medium with the laser light based on the recordingpulse signal generated by the recording pulse generation circuit. Dutyratios of the recording pulses are set to be constant when the linearvelocity v is v1≦v<v0 and when the linear velocity v is v0<v≦v2,respectively, and the power level Pbt of the inter-pulse is controlledso that (Pbt−Pe) is increased, depending on an increase in the linearvelocity v, when the linear velocity v is v1≦v<v0 and when the linearvelocity v is v0<v≦v2, respectively, where Pbt represents a power levelbetween the recording pulses for a linear velocity v of v1<v<v2, Perepresents a power level of the erase power for the linear velocity v,and v1<v0<v2.

In an optical information recording method according to the presentinvention, a mark or a space having a length corresponding to a lengthof a data recording code is formed by irradiating a rotating opticalinformation recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiation of the laser light with a power being switchedamong a plurality of power levels including at least a recording powerlevel and an erase power level. The method includes a linear velocitysetting step of setting a first linear velocity v1 and a second linearvelocity v2 that is higher than the first linear velocity v1 for therotating optical information recording medium, a recording pulsegeneration step of generating a recording pulse signal, depending on aresult of setting by the linear velocity setting step, and a laser drivestep of irradiating the optical information recording medium with thelaser light based on the recording pulse signal generated by therecording pulse generation step. In a laser drive step, a power level ofthe laser light is controlled in such a manner that Pbt1≦Pe1 andPe2<Pbt2≦Pwa2 is satisfied, where Pbt1 represents a first inter-pulsepower level indicating a power level between recording pulses for thefirst linear velocity v1, Pbt2 represents a second inter-pulse powerlevel indicating a power level between the recording pulses for thesecond linear velocity v2, Pwa2 represents a recording power levelindicating a power level of the recording power for the second linearvelocity v2, Pe1 represents a first erase power level indicating a powerlevel of the erase power for the first linear velocity v1, and Pe2represents a second erase power level indicating a power level of theerase power for the second linear velocity v2.

In another optical information recording method according to the presentinvention, a mark or a space having a length corresponding to a lengthof a data recording code is formed by irradiating a rotating opticalinformation recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiation of the laser light with a power being switchedamong a plurality of power levels including at least a recording powerlevel and an erase power level. The method includes a linear velocitysetting step of setting a first linear velocity v1 and a second linearvelocity v2 that is higher than the first linear velocity v1 for therotating optical information recording medium, a recording pulsegeneration step of generating a recording pulse signal, depending on aresult of setting by the linear velocity setting step, and a laser drivestep of irradiating the optical information recording medium with thelaser light based on the recording pulse signal generated by therecording pulse generation step. In the laser drive step, a power levelof the laser light is controlled in such a manner that Pbt1≦Pe1 andPe2<Pwb2<Pwa2 is satisfied, and a waveform of the laser light for thesecond linear velocity v2 is caused to be a stepwise waveform such thata recording pulse of the power level Pwb2 is provided immediately aftera recording pulse of the power level Pwa2, where Pbt1 represents a firstinter-pulse power level indicating a power level between recordingpulses for the first linear velocity v1, Pwa2 represents a recordingpower indicating a power level of the recording power for the secondlinear velocity v2, Pwb2 represents a second recording power indicatinga power level of a second recording power for the second linear velocityv2, Pe1 represents a first erase power level indicating a power level ofthe erase power for the first linear velocity v1, and Pe2 represents asecond erase power level indicating a power level of the erase power forthe second linear velocity v2.

In still another optical information recording method according to thepresent invention, a mark or a space having a length corresponding to alength of a data recording code is formed by irradiating a rotatingoptical information recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiation of the laser light with a power being switchedamong a plurality of power levels including at least a recording powerlevel and an erase power level. The method includes a linear velocitysetting step of setting a first linear velocity v1, which is a lowerlimit, and a second linear velocity v2, which is an upper limit, withrespect to the rotating optical information recording medium, arecording pulse generation step of generating a recording pulse signal,depending on a result of setting by the linear velocity setting circuit,and a laser drive step of irradiating the optical information recordingmedium with the laser light based on the recording pulse signalgenerated by the recording pulse generation circuit. Pbt1≦Pe1 andPe2<Pwb2<Pwa2 are satisfied, the laser light is emitted while switchingpowers among the recording power level, the first erase power level andthe first inter-pulse power level, when the linear velocity v isv1<v<v0, a waveform of the laser light is caused to be a stepwisewaveform such that a recording pulse of the power level Pwb2 is providedimmediately after a recording pulse of the power level Pwa2, when thelinear velocity v is v0<v<v2, and the power level Pwb of the secondrecording power is controlled so that (Pwb−Pe) is increased, dependingon an increase in the linear velocity v. Pbt1 represents a firstinter-pulse power level indicating a power level between recordingpulses for the first linear velocity v1, Pwa2 represents a recordingpower indicating a power level of the recording power for the secondlinear velocity v2, Pwb2 represents a second recording power indicatinga power level of a second recording power for the second linear velocityv2, Pe1 represents a first erase power level indicating a power level ofthe erase power for the first linear velocity v1, Pe2 represents asecond erase power level indicating a power level of the erase power forthe second linear velocity v2, v1<v0<v2, Pwb represents a power level ofthe second recording power for a linear velocity v of v1<v<v2, and Perepresents a power level of the erase power for the linear velocity v.

In still another optical information recording method according to thepresent invention, a mark or a space having a length corresponding to alength of a data recording code is formed by irradiating a rotatingoptical information recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiation of the laser light with a power being switchedamong a plurality of power levels including at least a recording powerlevel and an erase power level. The method includes a linear velocitysetting step of setting a first linear velocity v1, which is a lowerlimit, and a second linear velocity v2, which is an upper limit, withrespect to the rotating optical information recording medium, arecording pulse generation step of generating a recording pulse signal,depending on a result of setting by the linear velocity setting circuit,and a laser drive step of irradiating the optical information recordingmedium with the laser light based on the recording pulse signalgenerated by the recording pulse generation circuit. Duty ratios of therecording pulses are set to be constant when the linear velocity v isv1≦v<v0 and when the linear velocity v is v0<v≦v2, respectively, and thepower level Pbt of the inter-pulse is controlled so that (Pbt−Pe) isincreased, depending on an increase in the linear velocity v, when thelinear velocity v is v1≦v<v0 and when the linear velocity v is v0<v≦v2,respectively, where Pbt represents a power level between the recordingpulses for a linear velocity v of v1<v<v2, Pe represents a power levelof the erase power for the linear velocity v, and v1<v0<v2 is satisfied.

An optical information recording medium according to the presentinvention, which is to be used for recording data by the opticalinformation recording method of the present invention, includesinformation recorded thereon that indicates values of the firstinter-pulse power level Pbt1 and the second inter-pulse power level Pbt2is recorded on the optical information recording medium.

Another optical information recording medium according to the presentinvention, which is to be used for recording data by the opticalinformation recording method of the present invention, includesinformation recorded thereon that indicates values of the firstinter-pulse power level Pbt1 and the second recording power level Pwb2recorded on the optical information recording medium.

Still another optical information recording medium according to thepresent invention, which is to be used for recording data by the opticalinformation recording method of the present invention, includesinformation recorded thereon that indicates a value of the secondrecording power level Pwb2 is recorded on the optical informationrecording medium.

Still another optical information recording medium according to thepresent invention, which is to be used for recording data by the opticalinformation recording method of the present invention, includesinformation recorded thereon that indicates a value of the firstinter-pulse power level Pbt1 is recorded on the optical informationrecording medium.

Still another optical information recording medium according to thepresent invention, which is to be used for recording data by the opticalinformation recording method of the present invention, includesinformation recorded thereon that indicates values of the inter-pulsepower level Pbt and the duty ratio of the recording pulse is recorded onthe optical information recording medium.

Still another optical information recording medium according to thepresent invention, which is to be used for recording data by the opticalinformation recording method of the present invention, includesinformation recorded thereon that indicates a value of a correctionamount of an edge position of the recording pulse is recorded on theoptical information recording medium.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an schematic structure of an opticalinformation recording device according to Embodiment 1 of the presentinvention.

FIG. 2 is a flowchart showing an operation of the optical informationrecording device of Embodiment 1.

FIGS. 3 and 4 are signal waveform diagrams for explaining an operationof the optical information recording device of Embodiment 1.

FIG. 5 is a flowchart showing an operation of an optical informationrecording device according to Embodiment 2 of the present invention.

FIGS. 6 and 7 are signal waveform diagrams for explaining an operationof the optical information recording device of Embodiment 2.

FIGS. 8A to 8C are schematic diagrams for explaining an operation of anoptical information recording device according to Embodiment 3 of thepresent invention.

FIGS. 9A to 9D are schematic diagrams for explaining a variation of theoperation of the optical information recording device of Embodiment 3.

FIGS. 10A to 10D are schematic diagrams for explaining another variationof the operation of the optical information recording device ofEmbodiment 3.

FIGS. 11A to 11C are schematic diagrams for explaining still anothervariation of the operation of the optical information recording deviceof Embodiment 3.

FIGS. 12A to 12E are schematic diagrams for explaining still anothervariation of the operation of the optical information recording deviceof Embodiment 3.

FIGS. 13A to 13F are schematic diagrams for explaining still anothervariation of the operation of the optical information recording deviceof Embodiment 3.

FIGS. 14A and 14B are schematic diagrams for explaining still anothervariation of the operation of the optical information recording deviceof Embodiment 3.

FIGS. 15A and 15B are schematic diagrams for explaining still anothervariation of the operation of the optical information recording deviceof Embodiment 3.

FIGS. 16 and 17 are signal waveform diagrams for explaining an operationof a conventional optical information recording device.

FIG. 18 is a signal waveform diagram for explaining another conventionaloptical information recording device.

FIG. 19 is a signal waveform diagram for explaining still anotherconventional optical information recording device.

BEST MODE FOR CARRYING OUT THE INVENTION

In an optical information recording device according to an embodiment ofthe present invention, the laser drive circuit controls a power level ofthe laser light in such a manner that Pbt1≦Pe1 and Pe2<Pbt2≦Pwa2 issatisfied, where Pbt1 represents a first inter-pulse power levelindicating a power level between recording pulses for the first linearvelocity v1, Pbt2 represents a second inter-pulse power level indicatinga power level between the recording pulses for the second linearvelocity v2, Pwa2 represents a recording power level indicating a powerlevel of the recording power for the second linear velocity v2, Pe1represents a first erase power level indicating a power level of theerase power for the first linear velocity v1, and Pe2 represents asecond erase power level indicating a power level of the erase power forthe second linear velocity v2.

Therefore, the inter-pulse power level Pbt1 for a low linear velocityand the inter-pulse power level Pbt2 for a high linear velocity can beset to be different from each other. In addition, when an erase powerfor each linear velocity is used as a reference, the inter-pulse powerPbt1 can be set to be lower than the erase power Pe1 for a low linearvelocity, while the inter-pulse power Pbt2 can be set to be higher thanthe erase power Pe2 for a high linear velocity. As a result, it ispossible to form a mark without distortion over a wide linear velocityrange, thereby allowing accurate data recording.

Preferably, the laser drive circuit controls the second inter-pulsepower level Pbt2 to be Pbt2=Pwa2, and controls a waveform of therecording pulse to be a rectangular wave.

Preferably, the laser drive circuit controls the inter-pulse power levelPbt so that (Pbt−Pe) is increased between Pbt1 and Pbt2, depending on anincrease in the linear velocity v, where Pbt represents a power levelbetween the recording pulses for a linear velocity v of v1<v<v2, and Perepresents a power level of the erase power for the linear velocity v.

Preferably, a waveform of the recording pulse is a rectangular wave fora predetermined linear velocity of v0 or more, v0 having a relationshipv1<v0<v2.

An optical information recording device according to an embodiment ofthe present invention forms a mark or a space having a lengthcorresponding to the length of a data recording code by irradiating arotating optical information recording medium with laser light to changeoptical characteristics of a photosensitive recording layer. The mark isformed by irradiation of the laser light with a power being switchedamong a plurality of power levels including at least a recording powerlevel and an erase power level. The device includes a linear velocitysetting circuit for setting the first linear velocity v1 and the secondlinear velocity v2 that is higher than the first linear velocity v1 forthe rotating optical information recording medium, a recording pulsegeneration circuit for generating a recording pulse signal, depending ona result of setting by the linear velocity setting circuit, and a laserdrive circuit for irradiating the optical information recording mediumwith the laser light based on the recording pulse signal generated bythe recording pulse generation circuit. The laser drive circuit controlsa power level of laser light in such a manner that Pe1≦Pbt1,Pe2<Pbt2≦Pwa2 and (Pbt1−Pe1)/(Pwa1−Pe1)<(Pbt2−Pe2)/(Pwa2−pe2) aresatisfied, where Pbt1 represents a first inter-pulse power levelindicating the power level between the recording pulses for the firstlinear velocity v1, Pbt2 represents a second inter-pulse power levelindicating the power level between the recording pulses for the secondlinear velocity v2, Pwa2 represents a recording power level indicatingthe power level of the recording power for the second linear velocityv2, Pe1 represents a first erase power level indicating the power levelof the erase power for the first linear velocity v1, and Pe2 representsa second erase power level indicating the power level of the erase powerfor the second linear velocity v2.

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings.

(Embodiment 1)

FIG. 1 is a block diagram showing a schematic structure of an opticalinformation recording device 100 according to Embodiment 1 of thepresent invention.

Reference numeral 1 indicates an optical disc onto/from which data isrecorded/reproduced. Reference numeral 2 indicates a system controlcircuit that controls the whole optical information recording device100. Reference numeral 3 indicates a modulation circuit that generates abinary recording data signal corresponding to data to be recorded.Reference numeral 4 indicates a recording pulse generation circuit thatgenerates a pulse for driving a laser, depending on the recording datasignal. Reference numeral 5 indicates a laser drive circuit thatmodulates a current for driving a laser in an optical head 6, dependingon the pulse output by the recording pulse generation circuit. Referencenumeral 6 indicates an optical head that focuses laser light toirradiate the optical disc 1. Reference numeral 7 indicates a linearvelocity setting circuit that controls a linear velocity (i.e.,rotational speed) of the optical disc 1. Reference numeral 8 indicates aspindle motor that rotates the optical disc 1. Reference numeral 9indicates a reproduced signal processing circuit that processes awaveform of a reproduced signal based on light reflected from theoptical disc 1. Reference numeral 10 indicates a demodulation circuitfor obtaining reproduced data.

Next, operations of the optical information recording device 100 ofEmbodiment 1 will be described with reference to a flowchart of FIG. 2and operation diagrams of FIGS. 3 and 4.

FIG. 2 is a flowchart showing the operation of the optical informationrecording device 100 of Embodiment 1. FIG. 3 is a waveform diagramshowing an operation of the optical information recording device 100 ofEmbodiment 1 when recording is performed at a low linear velocity. FIG.4 is a waveform diagram showing an operation thereof when recording isperformed at a high linear velocity. FIGS. 3 and 4 show an operation ofrecording a mark having a code length of 5T. As used herein, Trepresents a channel clock cycle. In Embodiment 1, a recording pulsesignal 12 composed of a total of three recording pulses is used torecord a mark having a code length of 5T. A mark having a code lengthother than 5T is recorded using a different number of recording pulsesor/and a recording pulse sequence having a different whole length,depending on an increase or a decrease in the code length.

FIGS. 3 and 4 show a waveform of a channel clock signal, a waveform of amodulation signal 11, a waveform of the recording pulse signal 12, awaveform of an inter-pulse level control signal 13, a light emissionwaveform of laser light 14, and states of respective tracks 301 and 401after respective marks 302 and 402 are recorded by the laser light 14.

For recording, initially, in a linear velocity setting step STEP201(hereinafter abbreviated such as S201), the linear velocity settingcircuit 7 controls the rotational speed of the spindle motor 8 inaccordance with an instruction from the system control circuit 2 torotate the optical disc 1 at a predetermined linear velocity.Thereafter, in a seek operation step S202, the optical head 6 seeks apredetermined recording area on the optical disc 1.

Next, an operation of recording at the low linear velocity (i.e.,recording with a low transfer rate) in Embodiment 1, particularly anoperation of recording data, will be described.

In a recording and erase power determination step S203, the systemcontrol circuit 2 determines an optimum recording power level Pwa1 anderase power level Pe1 for this low linear velocity and outputs a powersetting signal 15 to the laser drive circuit 5. The recording powerlevel Pwa1 and the erase power level Pe1 may be determined by performingtest recording on the optical disc 1. Alternatively, when informationthat indicates the recording power level Pwa1 and the erase power levelPe1 previously are recorded in a control track area of the optical disc1, the recording power level Pwa1 and the erase power level Pe1 may bedetermined by reading the information.

Similar to S203, in an inter-pulse level determination step S204, thesystem control circuit 2 determines a interpulse power level Pbt1 forthe low linear velocity and outputs the power setting signal 15 to thelaser drive circuit 5. Here, in the case of the low linear velocity, theinter-pulse power level Pbt1 is set to be lower than the erase powerlevel Pe1.

Thereafter, in a modulation step S205, recording data from the systemcontrol circuit 2 is modulated by the modulation circuit 3 based on thechannel clock signal of FIG. 3. The modulation circuit 3 outputs themodulation signal 11 of FIG. 3. Next, in a recording pulse sequencesignal and inter-pulse signal generation step S206, the recording pulsegeneration circuit 4 outputs the recording pulse signal 12 and theinter-pulse level control signal 13 as shown in FIG. 3 to the laserdrive circuit 5 based on the modulation signal 11 output from themodulation circuit 3.

Thereafter, in a laser drive step S207, the laser drive circuit 5modulates a power level of the laser light 14. This power level isdetermined based on signal levels of the recording pulse signal 12 andthe inter-pulse level control signal 13. Specifically, the power levelof the laser light 14 is set to be the recording power level Pwa1 whenthe recording pulse signal 12 is “H”, set to be the inter-pulse powerlevel Pbt1 when the recording pulse signal 12 is “L” and the inter-pulselevel control signal 13 is “H”, and set to be the erase power level Pe1when the recording pulse signal 12 is “L” and the inter-pulse levelcontrol signal 13 is “L”. As a result, the light emission waveform ofthe laser light 14 has a power level that varies as shown in FIG. 3.

Thereafter, in a recording step S208, the laser light 14 forms the mark302 corresponding to the code length 5T on the recording track 301 asshown in FIG. 3.

In the case of the low linear velocity, a cycle Tw1 of the channel clocksignal is longer than the rising time and the falling time of laserlight, and therefore, the laser light 14 stably can perform modulationand light emission between each of the recording power level Pwa1, theerase power level Pe1 and the inter-pulse power level Pbt1. Therefore,the inter-pulse power level Pbt1 can be set to be lower than or equal tothe erase power level Pe1, so that the amount of heat when a rearportion of the mark 302 is being recorded can be equal to that of afront portion of the mark 302. As a result, the mark 302 can be formedwithout distortion, thereby making it possible to record dataaccurately.

Also, when recording is performed at the high linear velocity inEmbodiment 1 (i.e., recording with a high transfer rate), a signalwaveform of each section of the device and a recording pattern on atrack are as shown in FIG. 4.

A difference from the above-described recording at the low linearvelocity is that, in the inter-pulse level determination step S204, theinter-pulse power level Pbt2 is set to be higher than the erase powerlevel Pe2. Thereby, a temperature of the recording layer can beincreased sufficiently for the high linear velocity that otherwisecauses small heat accumulation. On the other hand, a modulation range ofa power level of the laser light 14 is relatively narrow compared withthat when recording is performed at the low linear velocity, andtherefore, a rising time and a falling time between each power level arealso short. In addition, the inter-pulse width can be prevented frombeing extremely small, and therefore, even in the case of the highlinear velocity, laser light can be modulated stably and emitted betweeneach power level.

As described above, an essence of Embodiment 1 is that the inter-pulsepower level Pbt1 for the low linear velocity is different from theinter-pulse power level Pbt2 for the high linear velocity, as shown inthe relationship between FIG. 3 and FIG. 4. In addition, when the erasepower levels Pe1 and Pe2 are used as references for respective linearvelocities, the inter-pulse power level Pbt1 is set to be lower than orequal to the erase power level Pe1 for the low linear velocity, whilethe inter-pulse power level Pbt2 is set to be higher than the erasepower level Pe2 for the high linear velocity. Thereby, it is possible toform a mark without distortion over a wide linear velocity range, sothat data can be recorded accurately.

(Embodiment 2)

Next, an operation of an optical information recording device accordingto Embodiment 2 of the present invention will be described with aflowchart of FIG. 5 and operation diagrams of FIGS. 6 and 7.

A structure of the optical information recording device of Embodiment 2and an operation thereof when recording is performed at a low linearvelocity are similar to those described in Embodiment 1. An operationthereof when recording is performed at a high linear velocityhereinafter will be described.

FIG. 5 is a flowchart showing the operation of the optical informationrecording device of Embodiment 2. FIGS. 6 and 7 are waveform diagramsshowing when recording is performed at the high linear velocity inEmbodiment 2. In FIGS. 6 and 7, an operation of recording a mark havinga code length of 5T is described as in FIGS. 3 and 4. FIGS. 5 and 6 showa waveform of a channel clock signal, a waveform of a modulation signal11, a waveform of a recording pulse signal 12, a waveform of a secondrecording power level control signal, a light emission waveform of laserlight 14, and states of respective tracks 301 and 401 after respectivemarks 302 and 402 are recorded by the laser light 14.

For recording, initially, in a linear velocity setting step 501, thelinear velocity setting circuit 7 controls the rotational speed of thespindle motor 8 in accordance with an instruction from the systemcontrol circuit 2 to rotate the optical disc 1 at a predetermined linearvelocity. Thereafter, in a seek operation step S502, the optical head 6seeks a predetermined recording area on the optical disc 1.

In a recording and erase power determination step S503, the systemcontrol circuit 2 determines an optimum recording power level Pwa2 anderase power level Pe2 for this high linear velocity and outputs a powersetting signal 15 to the laser drive circuit 5. The recording powerlevel Pwa2 and the erase power level Pe2 may be determined by performingtest recording on the optical disc 1 as in Embodiment 1. Alternatively,when information that indicates the recording power level and the erasepower level previously is recorded in a control track area of theoptical disc 1, the recording power level and the erase power level maybe determined by reading the information. Embodiment 2 is similar toEmbodiment 1 up to this point.

Thereafter, in a second recording power level determination step S504,the system control circuit 2 determines a second recording power levelPwb2 for the high linear velocity and outputs the power setting signal15 to the laser drive circuit 5.

Thereafter, in a modulation step S505, recording data from the systemcontrol circuit 2 is modulated by the modulation circuit 3 based on thechannel clock signal of FIG. 6. The modulation circuit 3 outputs themodulation signal 11 of FIG. 6. In a recording pulse signal and secondrecording power level signal generation step S506, the recording pulsegeneration circuit 4 outputs the recording pulse signal 12 and thesecond recording power level control signal 13 as shown in FIG. 6 to thelaser drive circuit 5 based on the modulation signal 11.

Thereafter, in a laser drive step S507, the laser drive circuit 5modulates a power level of the laser light 14. This power level isdetermined based on signal levels of the recording pulse signal 12 andthe second recording power level control signal 13. Specifically, thelaser light 14 is emitted at the first recording power level Pwa2 whenthe recording pulse signal 12 is “H”, at the second recording powerlevel Pwb2 when the recording pulse signal 12 is “L” and the secondrecording power level control signal is “H”, and at the erase powerlevel Pe2 when the recording pulse signal 12 is “L” and the secondrecording power level control signal is “L”. As a result, the lightemission waveform of the laser light 14 has a power level that varies asshown in FIG. 6.

Thereafter, in a recording step S508, the laser light 14 forms the mark602 corresponding to the code length 5T on the recording track 601 asshown in FIG. 6.

Embodiment 2 is different from Embodiment 1 in: (1) the laser drivecircuit 5 is controlled using the second recording power level controlsignal Pwb2 instead of the inter-pulse power level control signal Pbt1;(2) the laser light 14 is emitted, varying in a stepwise manner from thefirst recording power level Pwa2 to the second recording power levelPwb2 (where Pwa2>Pwb2>Pe2), by combination of signal levels of therecording pulse signal 12 and the second recording power level controlsignal 13; and (3) a width of each step of the stepwise light emissionwaveform is longer than ½ of a cycle Tw2 of the channel clock signal bycombination of the signal levels of the recording pulse signal 12 andthe second recording power level control signal 13.

According to the above-described embodiment, even when a linear velocityis higher than what can be handled by Embodiment 1, i.e., a high linearvelocity such that the sum of a rising time and a falling time is longerthan ½ of a cycle of a channel clock signal as in the conventionalexample of FIG. 17, it is possible to emit the laser light 14 stably ata desired power level as shown in FIG. 7. Also, a power level forrecording a front portion of the mark 702 is set to be higher than thatfor a rear portion of the mark 702. Therefore, even in the case of thehigh linear velocity (i.e., a relative speed between the laser light andthe recording medium is high), an amount of energy sufficient formelting a recording layer can be supplied upon starting recording themark 702, thereby making it possible to form the mark 702 stably. As aresult, data can be recorded accurately.

As described above, an essence of Embodiment 2 is that the secondrecording power level Pwb2 is provided when recording is performed atthe high linear velocity as shown in FIGS. 6 and 7. In addition, a lightemission waveform is changed in a stepwise manner such that a high powerlevel is used when recording the front portion of the mark 702, and thewidth of each step of the stepwise light emission waveform is longerthan ½ of the cycle Tw2, Tw3 of a channel clock signal. With thisoperation, it is possible to form a mark without distortion over a widerlinear velocity range than that of Embodiment 1. Thus, data can berecorded accurately.

(Embodiment 3)

In the above-described two Embodiments 1 and 2, recording is performedat two velocities, i.e., a low linear velocity and a high linearvelocity. On the other hand, in the CAV recording technique, a linearvelocity and a transfer rate vary continuously, depending on arecording/reproduction position on a medium. In such a case, preferably,by continuously joining a light emission waveform at the low linearvelocity with a light emission waveform at the high linear velocity, alight emission waveform at an intermediate linear velocity isdetermined.

FIGS. 8A to 8C show an example of inter-pulse power level settings whena linear velocity varies continuously in a range from v1 to v2 inEmbodiment 3. In this case, the laser light 14 is emitted in a lightemission waveform shown in FIG. 8B for the linear velocity v1, while thelaser light 14 is emitted in a light emission waveform shown in FIG. 8Cfor the linear velocity v2. A inter-pulse power level Pbt is changedsmoothly between a power level Pbt1=p1 for the linear velocity v1 and apower level Pbt2=p2 for the linear velocity v2. This change may beprovided in a linear form. Alternatively, the change may be provided ina manner that connects the two levels with a monotonic, smooth curve.Alternatively, the change may be provided in a monotonic, stepwise form.

It is desirable that the inter-pulse power level Pbt is set to beincreased relatively with respect to the erase power level Pe, dependingon an increase in a linear velocity. In other words, it is desirablethat the inter-pulse power level Pbt is set so that (Pbt−Pe) isincreased, depending on an increase in a linear velocity.

The above-described method of continuously changing the inter-pulsepower level depending on the linear velocity has an advantage of easilyconstructing the device over the method of continuously changing therecording pulse width in the conventional example. The reason is asfollows. In order to change the recording pulse width, it is necessaryto provide a delay line in the recording pulse generation circuit, andfurther, it is necessary to adjust a delay time, resulting in acomplicated circuit, while the inter-pulse power level can be set onlyby increasing or decreasing a laser drive current using the laser drivecircuit 5.

FIGS. 9A to 9D are diagrams showing a variation of the embodiment ofFIGS. 8A to 8C, in which the inter-pulse power level Pbt is set to beequal to the recording power level Pwa2 for the maximum linear velocityv2 as shown in FIG. 9D (i.e., a light emission waveform having arectangular wave).

FIGS. 10A to 10D are diagrams showing another variation of theembodiment of FIGS. 8A to 8C, in which, when a linear velocity is higherthan v0, the inter-pulse power level Pbt is set to be equal to therecording power level Pwa2 and the recording pulse width is changeddepending on the linear velocity.

In the case of the embodiments of FIGS. 9A to 9D and FIGS. 10A to 10D,the laser light 14 needs to be modulated at only two power levels, i.e.,the recording power level Pwa2 and the erase power level Pe2, for a highlinear velocity required for the high speed drive of a laser. Therefore,the structure of the laser drive circuit can be simplified and themanufacturing cost of the circuit can be advantageously reduced.

FIGS. 11A to 11C are diagrams showing still another variation ofEmbodiment 3. FIGS. 11A to 11C show an exemplary second recording powerlevel setting when a linear velocity varies continuously in a range fromv1 to v2. In this case, the laser light 14 is emitted in the waveform ofFIG. 6 or 7 for both the linear velocities v1 and v2.

The second recording power level desirably is set to increase from Pwb1to Pwb2 relatively with respect to the erase power levels Pe1 and Pe2 asthe linear velocity increases from v1 to v2. In other words, the secondrecording power level desirably is set so that a value (Pwb−Pe) obtainedby subtracting the erase power level from the second recording powerlevel is increased, depending on an increase in the linear velocity.

In this embodiment, the power level does not vary depending on arecording pulse sequence. Therefore, it is preferable to operate withina high linear velocity range, in which a higher cooling rate in arecording layer is obtained.

FIGS. 12A to 12E are diagrams showing an embodiment in which recordingcan be performed at a further lower linear velocity in addition to thelinear velocity range of the embodiment of FIG. 11 in which recordingcan be performed. In FIG. 12, recording is performed while changing theduty ratio of a recording pulse, depending on a linear velocity, as inthe conventional example in a range of v1≦(linear velocity)≦v0 in whichthe sum of a rising time and a falling time is smaller than therecording pulse width (or the inter-pulse width). In addition, in arange of v0≦(linear velocity)≦v2 (i.e., a linear velocity higher thanv0), the light emission waveform is switched to a stepwise form, such asthat described in Embodiment 2, and recording is performed whilechanging the second recording power level Pwb2, depending on the linearvelocity. As a result, data can be recorded accurately in a range widerthan that of the embodiment of FIG. 11.

FIGS. 13A to 13F are diagrams showing an embodiment in which the dutyratio of the recording pulse is changed depending on the linearvelocity, and the power level of the inter-pulse is changedcontinuously. In FIGS. 13A to 13F, ranges of v1≦(linear velocity)≦v0 andv0≦(linear velocity)≦v2 have predetermined respective duty ratios ofrecording pulses different from each other. In addition, the linearvelocity is continuously changed in each of the ranges of v1≦(linearvelocity)≦v0 and v0≦(linear velocity)≦v2.

As the conventional example, when only the duty ratio of the recordingpulse is changed depending on the linear velocity, the duty ratiousually is set to be only discrete. Therefore, recording characteristicsdisadvantageously vary depending on the recording linear velocity (therecording position in the case of the CAV recording technique). Incontrast to this, in the example of FIGS. 13A to 13F, the power level ofthe inter-pulse is changed in a linear velocity range in which the dutyratio is uniform, thereby making it possible to reduce a variation inthe recording characteristics.

Further, in addition to the embodiment of FIG. 13A to 13F, in order toavoid an influence of heat interference between marks, edge positions ofrecording pulses (e.g., a front edge position of a leading recordingpulse and a rear edge position of a last recording pulse) may becorrected at each of the linear velocities v1 and v0 with reference to achannel clock. When a recording device or a recording medium hasinformation that indicates the above-described corrected value, thefollowing method is preferably used.

In v1≦(linear velocity)<v0 an edge position corrected at the linearvelocity v1 is used, while in v0≦(linear velocity)≦v2 an edge positioncorrected at the linear velocity v0 is used. In this case, it is notnecessary for a recording device or a recording medium to haveinformation for correcting a number of edge positions for each minutelinear velocity intervals. Therefore, the structure of the recordingdevice can be simplified and an area of the recording medium that isrequired for having information that indicates a correction value can bereduced, thereby making it possible to increase an area for recordingdata.

FIGS. 14A and 14B and FIGS. 15A to 15B are diagrams showing stillanother variation of Embodiment 3. In the example of Embodiment 1described above with reference to FIGS. 3 and 4, the inter-pulse powerPbt1 is set to be lower than or equal to the erase power level Pe1 forthe low linear velocity v1. Alternatively, as shown in FIGS. 14A and15A, the inter-pulse power level Pbt1 may be set to be higher than orequal to the erase power level Pe1 for the low linear velocity v1.

As an example of the power setting method in the above-describedEmbodiments 1 and 3, the recording power level Pwa1, the erase powerlevel Pe1 and the inter-pulse power level Pbt1 for the low linearvelocity v1, and the recording power level Pwa2, the erase power levelPe2 and the inter-pulse power level Pbt2 for the high linear velocity v2are set in a manner that satisfies the Formula 1 as follows.(Pbt1−Pe1)/(Pwa1−Pe1)<(Pbt2−Pe2)/(Pwa2−pe2)  (Formula 1)

In the embodiment of the present invention in which the power level ischanged depending on the linear velocity as shown in FIGS. 8–15B, thesimplest method of determining a value of a varying power level is suchthat values of optimum power levels for the linear velocities v1, v2 andv0 are determined by test recording, and a power level between each ofthem is determined by interpolation from the power levels at v1, v2 andv0.

Further, in each of the above-described embodiments, when informationthat indicates a power level varying depending on a linear velocitypreviously is recorded in a control track of a medium (i.e., an arearecording information about the medium), it is advantageously possibleto determine a power level corresponding to a linear velocityimmediately after the medium is loaded into an optical informationrecording device. This power level information may be recorded onto amedium by an optical information recording device or may be previouslyrecorded during production of a medium.

As described above, in the embodiment of the present invention, bychanging the inter-pulse power level Pbt, depending on the linearvelocity, laser light can be stably modulated over a wide linearvelocity range and a mark without distortion can be formed, therebymaking it possible to record data accurately.

Also in the embodiment of the present invention, by providing the secondrecording power level for recording at a high linear velocity andcausing a light emission waveform to vary so that it has a high,stepwise power level when recording a front portion of a mark, laserlight can be modulated stably over a wider linear velocity range and amark without distortion can be formed, thereby making it possible torecord data accurately.

Note that the above-described modulation technique, the length andposition of each pulse and the like are not limited to those describedin each of the above-described embodiments and can be set appropriatelydepending on recording conditions or a medium. Further, in order toavoid an influence of heat interference between marks, an edge positionof a recording pulse may be corrected. Furthermore, a cooling pulse maybe added after a recording pulse or a recording pulse sequence.

Further, the above-described method can be applied to any optical discmedium that has optical characteristics different between a mark and aspace, such as those made of a phase change material, a magneto-opticalmaterial, a pigment material or the like.

Further, an effect similar to that described above can be obtained in apersonal computer, a server and a recorder using the optical informationrecording method, the optical information recording device and theoptical information recording medium of the embodiment of the presentinvention.

As described above, according to the optical information recordingmethod of the embodiment of the present invention, by changing theinter-pulse power level Pbt, depending on the linear velocity, laserlight can be stably modulated over a wide linear velocity range and amark without distortion can be formed, thereby making it possible torecord data accurately.

Further, according to the optical information recording method of theembodiment of the present invention, by providing a second recordingpower level for recording at a high linear velocity and causing a lightemission waveform to vary so that it has a high, stepwise power levelwhen recording a front portion of a mark, laser light can be stablymodulated over a wider linear velocity range and a mark withoutdistortion can be formed, thereby making it possible to record dataaccurately.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, it is possibleto provide an optical information recording method, an opticalinformation recording device and an optical information recording mediumthat can record/reproduce data onto/from the same medium with stabilityand satisfactory signal quality over a wide linear velocity range.

1. An optical information recording device, wherein a mark or a spacehaving a length corresponding to a length of a data recording code isformed by irradiating a rotating optical information recording mediumwith laser light to change optical characteristics of a photosensitiverecording layer, and the mark is formed by irradiating the rotatingoptical information recording medium with the laser light with a powerbeing switched among a plurality of power levels including at least arecording power level and an erase power level, the device comprising: alinear velocity setting portion for setting a first linear velocity v1and a second linear velocity v2 that is higher than the first linearvelocity v1 for the rotating optical information recording medium; arecording pulse generation portion for generating a recording pulsesignal composed of a recording pulse and/or a recording pulse train,depending on a result of setting by the linear velocity setting portion;and a laser drive portion for irradiating the optical informationrecording medium with the laser light based on the recording pulsesignal generated by the recording pulse generation portion, wherein thelaser drive portion controls a power level of the laser light in such amanner that Pbt1≦Pe1 and Pe2<Pbt2<Pwa2 is satisfied, where Pbt1represents a first inter-pulse power level indicating a power levelbetween recording pulses in the recording pulse train for the firstlinear velocity v1, Pbt2 represents a second inter-pulse power levelindicating a power level between the recording pulses in the recordingpulse train for the second linear velocity v2, Pwa2 represents arecording power level indicating a power level of the recording powerfor the second linear velocity v2, Pe1 represents a first erase powerlevel indicating a power level of the erase power for the first linearvelocity v1, and Pe2 represents a second erase power level indicating apower level of the erase power for the second linear velocity v2.
 2. Theoptical information recording device according to claim 1, wherein thelaser drive portion controls the inter-pulse power level Pbt so that(Pbt−Pe) is increased between Pbt1 and Pbt2, depending on an increase inthe linear velocity v, where Pbt represents a power level between therecording pulses in the recording pulse train for a linear velocity v ofv1<v<v2, and Pe represents a power level of the erase power for thelinear velocity v.
 3. The optical information recording device accordingto claim 1, wherein a waveform of the recording pulse is a rectangularwave for a predetermined linear velocity of v0 or more, v0 satisfying arelationship v1<v0<v2.
 4. An optical information recording device,wherein a mark or a space having a length corresponding to a length of adata recording code is formed by irradiating a rotating opticalinformation recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiating the rotating optical information recording mediumwith the laser light with a power being switched among a plurality ofpower levels including at least a recording power level and an erasepower level, the device comprising: a linear velocity setting portionfor setting a first linear velocity v1 and a second linear velocity v2that is higher than the first linear velocity v1 for the rotatingoptical information recording medium; a recording pulse generationportion for generating a recording pulse signal composed of a recordingpulse and/or a recording pulse train, depending on a result of settingby the linear velocity setting portion; and a laser drive portion forirradiating the optical information recording medium with the laserlight based on the recording pulse signal generated by the recordingpulse generation portion, wherein the laser drive portion controls apower level of the laser light in such a manner that Pbt1≦Pe1 andPe2<Pwb2<Pwa2 is satisfied, and a waveform of the laser light for thesecond linear velocity v2 is set to be a stepwise waveform such that arecording pulse of the power level Pwb2 is provided immediately after arecording pulse of the power level Pwa2, where Pbt1 represents a firstinter-pulse power level indicating a power level between recordingpulses in the recording pulse train for the first linear velocity v1,Pwa2 represents a recording power indicating a power level of therecording power for the second linear velocity v2, Pwb2 represents asecond recording power indicating a power level of a second recordingpower for the second linear velocity v2, Pe1 represents a first erasepower level indicating a power level of the erase power for the firstlinear velocity v1, and Pe2 represents a second erase power levelindicating a power level of the erase power for the second linearvelocity v2.
 5. The optical information recording device according toclaim 4, wherein the recording pulse generation portion sets a width ofeach step of the stepwise waveform to be longer than ½ of a channelclock cycle for the second linear velocity v2.
 6. An optical informationrecording device, wherein a mark or a space having a lengthcorresponding to a length of a data recording code is formed byirradiating a rotating optical information recording medium with laserlight to change optical characteristics of a photosensitive recordinglayer, and the mark is formed by irradiating the rotating opticalinformation recording medium with the laser light with a power beingswitched among a plurality of power levels including at least arecording power level and an erase power level, the device comprising: alinear velocity setting portion for setting a first linear velocity v1,which is a lower limit, and a second linear velocity v2, which is anupper limit, with respect to the rotating optical information recordingmedium, a recording pulse generation portion for generating a recordingpulse signal composed of a recording pulse and/or a recording pulsetrain, depending on a result of setting by the linear velocity sellingportion; and a laser drive portion for irradiating the opticalinformation recording medium with the laser light based on the recordingpulse signal generated by the recording pulse generation portion,wherein Pbt1≦Pe1 and Pe2<Pwb2<Pwa2 are satisfied, the laser light isirradiated while switching powers among the recording power level, thefirst erase power level and the first inter-pulse power level, when thelinear velocity v is v1<v<v0, where v0 represents a predetermined linearvelocity, a waveform of the laser light is set to be a stepwise waveformsuch that a recording pulse of the power level Pwb2 is providedimmediately after a recording pulse of the power level Pwa2, when thelinear velocity v is v0<v<v2, and the power level Pwb of the secondrecording power is controlled so that (Pwb−Pe) is increased, dependingon an increase in the linear velocity v, where Pbt1 represents a firstinter-pulse power level indicating a power level between recordingpulses in the recording pulse train for the first linear velocity v1,Pwa2 represents a recording power indicating a power level of therecording power for the second linear velocity v2, Pwb2 represents asecond recording power indicating a power level of a second recordingpower for the second linear velocity v2, Pe1 represents a first erasepower level indicating a power level of the erase power for the firstliner velocity v1, Pe2 represents a second erase power level indicatinga power level of the erase power for the second linear velocity v2,v1<v<v2 is satisfied, Pwb represents a power level of the secondrecording power for a linear velocity v of v1<v<v2, and Pe represents apower level of the erase power for the liner velocity v.
 7. The opticalinformation recording device according to claim 6, wherein the recordingpulse generation portion sets a width of each step of the stepwisewaveform to be longer than ½ of a channel clock cycle for the secondlinear velocity v2.
 8. An optical information recording device, whereina mark or a space having a length corresponding to a length of a datarecording code is formed by irradiating a rotating optical informationrecording medium with laser light to change optical characteristics of aphotosensitive recording layer, and the mark is formed by irradiatingthe rotating optical information recording medium with the laser lightwith a power being switched among a plurality of power levels includingat least a recording power level and en erase power level, the devicecomprising: a linear velocity setting portion for setting a first linearvelocity v1, which is a lower limit, and a second linear velocity v2,which is an upper limit with respect to the rotating optical informationrecording medium, a recording pulse generation portion for generating arecording pulse signal composed of a recording pulse and/or a recordingpulse train, depending on a result of setting by the linear velocitysetting portion; and a laser drive portion for irradiating the opticalinformation recording medium with the laser light based on the recordingpulse signal generated by the recording pulse generation portion,wherein duty ratios of the recording pulses are set to be constant whenthe linear velocity v is v1≦v<v0 and when the linear velocity v isv0<v≦v2, respectively, and the power level Pbt of the inter-pulse iscontrolled so that (Pbt−Pe) is increased, depending on an increase inthe linear velocity v, when the linear velocity v is v1≦v<v0 and whenthe linear velocity v is v0<v≦v2, respectively, where v0 represents apredetermined linear velocity, where Pbt represents a power levelbetween the recording pulses in the recording pulse train for a linearvelocity v of v1<v<v2, Pe represents a power level of the erase powerfor the linear velocity v, and v1<v0<v2.
 9. The optical informationrecording device according to claim 8, wherein a correction amount of anedge position of the recording pulse is controlled to be constant withreference to a channel clock cycle when the linear velocity v is v1≦v<v0end when the linear velocity v is v0<v≦v2, respectively, where v0represents a predetermined linear velocity.
 10. An optical informationrecording method, wherein a mark or a space having a lengthcorresponding to a length of a data recording code is formed byirradiating a rotating optical information recording medium with laserlight to change optical characteristics of a photosensitive recordinglayer, and the mark is formed irradiating the rotating opticalinformation recording medium with the laser light with a power beingswitched among a plurality of power levels including at least arecording power level and an erase power level, the method comprising: alinear velocity setting step of setting a first linear velocity v1 and asecond linear velocity v2 that is higher than the first linear velocityv1 for the rotating optical information recording medium; a recordingpulse generation step of generating a recording pulse signal composed ofa recording pulse and/or a recording pulse train, depending on a resultof setting by the linear velocity setting step; and a laser drive stepof irradiating the optical information recording medium with the laserlight based on the recording pulse signal generated by the recordingpulse generation step, wherein in a laser drive step, a power level ofthe laser light is controlled in such a manner that Pbt1≦Pe1 andPe2<Pbt2<Pwa2 is satisfied, where Pbt1 represents a first inter-pulsepower level indicating a power level between recording pulses in therecording pulse train for the first linear velocity v1, Pbt2 representsa second inter-pulse power level indicating a power level between therecording pulses in the recording pulse train for the second linearvelocity v2, Pwa2 represents a recording power level indicating a powerlevel of the recording power for the second linear velocity v2, Pe1represents a first erase power level indicating a power level of theerase power for the first linear velocity v1, and Pe2 represents asecond erase power level indicating a power level of the erase power forthe second linear velocity v2.
 11. The optical information recordingmethod according to claim 10, wherein in the laser drive step, theinter-pulse power level Pbt is controlled so that (Pbt−Pe) is increasedbetween Pbt1 and Pbt2, depending on an increase in the linear velocityv, where Pbt represents a power level between the recording pulses inthe recording pulse train for a linear velocity v of v1<v<v2, and Perepresents a power level of the erase power for the linear velocity v.12. The optical information recording method according to claim 10,wherein a waveform of the recording pulse is a rectangular wave for apredetermined linear velocity of v0 or more v0 satisfying a relationshipv1<v0<v2.
 13. The optical information recording method according toclaim 10, wherein data is recorded onto the optical informationrecording medium using a CAV recording technique.
 14. An opticalinformation recording medium to be used for recording data by theoptical information recording method according to claim 10, comprisinginformation recorded thereon that indicates values of the firstinter-pulse power level Pbt1 and the second inter-pulse power levelPbt2.
 15. An optical information recording method, wherein a mark or aspace having a length corresponding to a length of a data recording codeis formed by irradiating a rotating optical information recording mediumwith laser light to change optical characteristics of a photosensitiverecording layer, and the mark is formed by irradiating the rotatingoptical information recording medium with the laser light with a powerbeing switched among a plurality of power levels including at least arecording power level and an erase power level, the method comprising: alinear velocity setting step of setting a first linear velocity v1 and asecond linear velocity v2 that is higher than the first linear velocityv1 for the rotating optical information recording medium; a recordingpulse generation step of generating a recording pulse signal composed ofa recording pulse and/or a recording pulse train, depending on a resultof setting by the linear velocity setting step; and a laser drive stepof irradiating the optical information recording medium with the laserlight based on the recording pulse signal generated by the recordingpulse generation step, wherein in the laser drive step, a power level ofthe laser light is controlled in such a manner that Pbt1≦Pe1 andPe2<Pwb2<Pwa2 is satisfied, and a waveform of the laser light for thesecond linear velocity v2 is caused to be a stepwise waveform such thata recording pulse of the power level Pwb2 is provided immediately aftera recording pulse of the power level Pwa2, where Pbt1, represents afirst inter-pulse power level indicating a power level between recordingpulses in the recording pulse train for the first linear velocity v1,Pwa2 represents a recording power indicating a power level of therecording power for the second linear velocity v2, Pwb2 represents asecond recording power indicating a power level of a second recordingpower for the second linear velocity v2, Pe1 represents a first erasepower level indicating a power level of the erase power for the firstlinear velocity v1, and Pe2 represents a second erase power levelindicating a power level of the erase power for the second linearvelocity v2.
 16. The optical information recording method according toclaim 15, wherein in the recording pulse generation step, a width ofeach step of the stepwise waveform is set to be longer than ½ of achannel clock cycle for the second liner velocity v2.
 17. An opticalinformation recording medium to be used for recording data by theoptical information recording method according to claim 15, comprisinginformation recorded thereon that indicates values of the firstinter-pulse power level Pbt1 and the second recording power level Pwb2.18. The optical information recording method according to claim 15,wherein data is recorded onto the optical information recording mediumusing a CAV recording technique.
 19. An optical information recordingmethod, wherein a mark or a space having a length corresponding to alength of a data recording code is formed by irradiating a rotatingoptical information recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiating the rotating optical information recording mediumwith the laser light with a power being switched among a plurality ofpower levels including at least a recording power level and an erasepower level, the method comprising: a liner velocity setting step ofsetting a first liner velocity v1, which is a lower limit, and a secondlinear velocity v2, which is an upper limit, with respect to therotating optical information recording medium, a recording pulsegeneration step of generating a recording pulse signal composed of arecording pulse and/or a recording pulse train, depending on a result ofsetting by the linear velocity setting portion; and a laser drive stepof irradiating the optical information recording medium with the laserlight based on the recording pulse signal generated by the recordingpulse generation portion, wherein Pbt1≦Pe1 and Pe2<Pwb2<Pwa2 aresatisfied, the laser light is emitted while switching powers among therecording power level, the first erase power level and the firstinter-pulse power level, when the linear velocity v is v1<v<v0, where v0represents a predetermined linear velocity, a waveform of the laserlight is caused to be a stepwise waveform such that a recording pulse ofthe power level Pwb2 is provided immediately after a recording pulse ofthe power level Pwa2, when the linear velocity v is v0<v<v2, and thepower level Pwb of the second recording power is controlled so that(Pwb−Pe) is increased, depending on an increase in the linear velocityv, where Pbt1 represents a first inter-pulse power level indicating apower level between recording pulses in the recording pulse train forthe first linear velocity v1, Pwa2 represents a recording powerindicating a power level of the recording power for the second linearvelocity v2, Pwb2 represents a second recording power indicating a powerlevel of a second recording power for the second linear velocity v2, Pe1represents a first erase power level indicating a power level of theerase power for the first linear velocity v1, Pe2 represents a seconderase power level indicating a power level of the erase power for thesecond linear velocity v2, v1<v0<v2, Pwb represents a power level of thesecond recording power for a linear velocity v of v1<v<v2, and Perepresents a power level of the erase power for the linear velocity v.20. The optical information recording method according to claim 19,wherein in the recording pulse generation step, a width of each step ofthe stepwise waveform is set to be longer than ½ of a channel clockcycle for the second linear velocity v2.
 21. An optical informationrecording medium to be used for recording data by the opticalinformation recording method according to claim 19, comprisinginformation recorded thereon that indicates a value of the secondrecording power level Pwb2.
 22. An optical information recording mediumto be used for recording data by the optical information recordingmethod according to claim 19, comprising information recorded thereonthat indicates a value of the first inter-pulse power level Pbt1. 23.The optical information recording method according to claim 19, whereindata is recorded onto the optical information recording medium using aCAV recording technique.
 24. An optical information recording method,wherein a mark or a space having a length corresponding to a length of adata recording code is formed by irradiating a rotating opticalinformation recording medium with laser light to change opticalcharacteristics of a photosensitive recording layer, and the mark isformed by irradiating the rotating optical information recording mediumwith the laser light with a power being switched among a plurality ofpower levels including at least a recording power level and an erasepower level, the method comprising: a linear velocity setting step ofsetting a first linear velocity v1, which is a lower limit, end a secondlinear velocity v2, which is an upper limit, with respect to therotating optical information recording medium, a recording pulsegeneration step of generating a recording pulse signal composed of arecording pulse and/or a recording pulse train, depending on a result ofsetting by the linear velocity setting portion; and a laser drive stepof irradiating the optical information recording medium with the laserlight based on the recording pulse signal generated by the recordingpulse generation portion, wherein duty ratios of the recording pulsesare set to be constant when the linear velocity v is v1≦v<v0 and whenthe linear velocity v is v0<v≦v2, respectively, and the power level Pbtof the inter-pulse is controlled so that (Pbt−Pe) is increased,depending on an increase in the linear velocity v, when the linearvelocity v is v1≦v<v0 and when the linear velocity v is v0<v≦v2respectively, where v0 represents a predetermined linear velocity, wherePbt represents a power level between the recording pulses in therecording pulse train for a linear velocity v of v1<v<v2, Pe representsa power level of the erase power for the linear velocity v, andv1<v0<v2.
 25. The optical information recording method according toclaim 24, wherein a correction amount of an edge position of therecording pulse is controlled to be constant with reference to a channelclock cycle when the linear velocity v is v1≦v<v0 and when the linearvelocity v is v0<v≦v2, respectively, where v0 represents a predeterminedlinear velocity.
 26. An optical information recording medium to be usedfor recording data by the optical information recording method accordingto claim 25, comprising information recorded thereon that indicates avalue of a correction amount of an edge position of the recording pulse.27. An optical information recording medium to be used for recordingdata by the optical information recording method according to claim 24,comprising information recorded thereon that indicates values of theinter-pulse power level Pbt and the duty ratio of the recording pulse.28. The optical information recording method according to claim 24,wherein data is recorded onto the optical information recording mediumusing a CAV recording technique.